This invention generally relates to toolholders having an arrangement for adjusting the lead angle of an insert cutting edge, and is particularly concerned with a mounting assembly for pivotally mounting a cutting insert on either a cylindrical endmill body or a square shank toolholder.
Chamfering endmills are known in the prior art. Such endmills generally comprise a rotatable shaft, an endmill body having a radially-oriented wall, and a cutting insert secured into a pocket in the radially-oriented wall. The endmill body may terminate in a frusto-conical end, and the cutting insert may have a linear cutting edge that protrudes just over the frusto-conical end of the endmill body. The cutting edge of the insert is inclined at a desired chamfer angle with respect to the axis of rotation of the endmill which may be, for example, 45.degree.. Such chamfering endmills are used to bevel the edges of bores, corners, or other sharp surfaces that are created in the course of a machining operation.
The fixed mounting of the cutting insert in such prior art chamfering endmills limits them to only a single chamfer angle when beveling the edges of a workpiece. However, machining operations often require the cutting of chamfers of different angles. For example, if the workpiece is a drain plate having a plurality of circular drain holes, the chamfer angle around the edges of each of the holes would preferably be 30.degree. in order to render the promote draining. By contrast, in the case where the chamfer is used to guide one part of machinery into a tightly fitting orifice or opening, a chamfer angle of approximately 60.degree. would be useful in facilitating the rapid alignment and mating of the two machine components.
In the past, the need for the creation of chamfer cuts of different angles has necessitated the use of separate endmills. However, for small machine shops, the necessity of acquiring and maintaining a variety of different endmills in order to produce chamfers of 30.degree., 45.degree., 60.degree., etc., places an undesirable burden on the financial resources of such shops. It also necessitates the changing of the chamfering endmill every time the machine operator desires to cut chamfers of different angles, thus adding to the time and effort necessary to complete a particular series of machining operations.
Clearly, there is a need for a single chamfering endmill that is capable of making chamfering cuts at a variety of angles in order to eliminate the need for maintaining a separate milling cutter for every angle of chamfer cut. Ideally, such a milling cutter could be adjusted to cut chamfers of different angles quickly and easily so as to minimize the time and effort necessary to complete the machining operation. Finally, such a milling cutter should be capable of accurately and rigidly holding its cutting insert at different chamfer angles in order to produce accurate and high quality chamfer cuts.